YOUR E-MAIL ALERTS

BEIRUT, Lebanon (CNN) -- A German prosecutor heading the U.N. investigation into the assassination of Rafik Hariri has said the blast that killed the former Lebanese prime minister came from an explosives-packed truck.

Showing a photograph of a white cargo truck, Detlev Mehlis told a Beirut news conference Friday that a similar truck was used in the February 14 bombing in Beirut that killed 20 people, including Hariri.

Some officials had speculated that the blast was the result of explosives buried under the roadway -- an act they suggested would point to the involvement of Lebanese government officials or Syrian intelligence in Hariri's death.

In early April, the U.N. Security Council unanimously authorized an international investigation into the assassination.

The council voted after a U.N. fact-finding mission found that Lebanon's probe of the explosion had "serious flaws" and had "neither the capacity nor the commitment to reach a satisfactory and credible conclusion."

Hariri's death sparked massive demonstrations for and against the presence of Syrian troops and security agents in Lebanon.

Syria pulled its troops out of Lebanon at the end of April. Hariri was a key mover in getting a U.N. resolution to call on Syria to remove its troops and intelligence assets from Lebanon. Resolution 1559, passed last year, which also called on Lebanon to disband guerrilla groups.

A U.N. report released in March said the government of Syria "interfered" with governance in Lebanon in a heavy-handed way that was "the primary reason for the political polarization that ensued" before Hariri's death.

"It is obvious that this atmosphere provided the backdrop for the assassination of Mr. Hariri," the report said.

The Lebanese opposition has gone further, saying his assassination was an act of political retribution by Syria.

But Syria's government has said it had nothing to gain and everything to lose from Hariri's death.